It's very frustrating to destroy SAM's and getting back in your chopper to be shot down immediately by those same SAM's a minute later. It makes flying helicopters a nightmare and tedious.
Yeah, but the controls are so great they figured it would be best to keep putting you into situations where you are using them... What better way to show off? /sarcasm
Respawning SAMS, Vehicles and People are the future the US Military has just about cracked all 3 and are coming to a middle eastern country near you soon!